In this article, the polyaniline(PANI) spherical nanoparticles were synthesized by the way of emulsion polymerization. The effects of emulsifier concentration on the morphology and electrical properties were systematic studied. The structure of PANI prepared by this method was characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM). The electrochemical and capacitive behavior of PANI prepared by this way was systematically studied by cyclic voltammetry(CV) and electrochemical impedance spectroscopy (EIS) tests. The results showed that we obtained PANI spherical nanoparticles with diameter about 100nm and it had good electrochemical performance.